(CNN) -- Microsoft co-founder Paul Allen has pledged to give away most of his fortune to charity.
"[M]y philanthropic efforts will continue after my lifetime," Allen said in a statement Thursday. "I've planned for many years now that the majority of my estate will be left to philanthropy."
Allen's commitment comes as two of America's richest men, Bill Gates and Warren Buffett, have invited fellow billionaires to give half their wealth to charity. The unusual initiative is being promoted through the website, "The Giving Pledge," and is aimed at members of the Forbes 400 -- a list of the richest Americans.
Philanthropist Eli Broad, worth an estimated $6 billion, was the first to make the promise.
During his lifetime, Allen has donated more than a billion dollars through personal giving and his foundation.
The 57-year-old billionaire was diagnosed with non-Hodgkin's lymphoma in November 2009, more than 25 years after he was treated for Hodgkin's disease, a spokesman at his company Vulcan Inc. said at the time.
Non-Hodgkin's lymphoma, like the less-common Hodgkin's disease, is a cancer of the lymphatic system. Hodgkin's lymphoma is distinguished from the other by the presence of a certain type of cell.
Allen, who co-founded Microsoft with Bill Gates in the mid-1970s, was that company's chief technologist until he left in 1983, the year he was treated for Hodgkin's lymphoma, according to the website for his Paul G. Allen Family Foundations.
In March, Allen ranked 37th on the Forbes list of the world's billionaires. His net worth was $13.5 billion, according to the magazine.
Among Allen's business interests are the professional sports teams he owns, the NFL's Seattle Seahawks and the NBA's Portland Trail Blazers. He also is part owner of Major League Soccer's Seattle Sounders FC.